如果DAX中的条件是在行上创建笛卡尔联接

问题描述

没有If条件的Dax公式可以正常工作，但是一旦添加IF条件，行就会开始相乘。我相信它正在做笛卡尔积。

我的要求很简单。我只需要显示其中Sickness[Start_Date]>LASTDATE(Test[Date])

的那些行

完整的公式是-

Measure = 
var val = CALCULATE(MAX(Sickness[Start_Date]),FILTER(Sickness,Sickness[Start_Date]>LASTDATE(Test[Date])),ALL())
return
IF(val = BLANK(),1)

我有3个单独的表 Emp_data ，测试和疾病。

要复制这种情况，请按照以下步骤操作：

第一步：创建表 Emp_data

Emp_data = DATATABLE("Emp_no",INTEGER,"Name",STRING,{{101,"A"},{102,"B"},{103,"C"},{104,"D"},{105,"E"},{106,"F"},{107,"G"},{108,"I"},{109,"J"},{110,"K"},{111,"L"},{112,"N"},{113,"M"},{114,"O"},{115,"P"},{116,"Q"},{117,"R"},{118,"S"},{119,"T"},{120,"U"}
})

创建表格：测试

Test = DATATABLE("Emp_No","Date",DATETIME,"Result","3/10/2020",1},{101,"3/13/2020",2},"3/11/2020","3/12/2020","3/14/2020","3/15/2020","3/16/2020","4/20/2020","4/21/2020","4/22/2020","4/23/2020","4/24/2020","4/25/2020","4/26/2020","4/27/2020","5/5/2020",2}
})

创建表格疾病

Sickness = DATATABLE("Emp_no","Start_Date","End_Date","Sickness_Code","2/12/2020",30},50},"3/20/2020","3/30/2020","4/5/2020","4/10/2020",40},"3/1/2020","3/2/2020","3/21/2020","3/31/2020","4/30/2020","5/1/2020","5/15/2020","4/1/2020","4/15/2020","5/3/2020","5/16/2020","5/26/2020","5/27/2020","5/29/2020",40}}
)

第二步是在这3个表之间创建关系。 Emp_Data 和 Test 表具有一对多关系。我将过滤器方向更改为两者。思考可能会解决此问题。在表测试和疾病之间创建多对多关系。图像已附加

输出如下：

如果我删除了IF条件，那么我需要的是：

有人可以帮助我理解Power BI的这种行为吗？这看起来很奇怪。为什么在应用IF条件后行数会增加。预先感谢

解决方法

这是因为您为疾病数据表中的所有空白值分配了0值。删除if语句后，Power BI仅显示不返回空值的数据行。

要解决您的问题，请尝试以下更新的措施：

Measure = 
VAR val = CALCULATE(MAX(Sickness[Start_Date]),FILTER(Sickness,Sickness[Start_Date]>LASTDATE(Test[Date])),ALL())
VAR OneZero = IF(ISBLANK(val),1)
RETURN
IF(HASONEVALUE(Sickness[Emp_no],OneZero)